The first time her daughter was forced to have sex with a man for money was on her 15th birthday.

The teen, who has permanent name suppression, fled to police in November 2016.

Lata's partner, Avneensh Sehgal, is also facing a lengthy stint in prison after he pleaded guilty to dealing in underage people for sexual exploitation and receiving earnings from underage sexual exploitation.

After the pair appeared in court last week questions were asked about the men who paid for sex with the teenager.

Some people were outraged that the men had not been prosecuted and others criticised police for not investigating them.

Detective Inspector Colin Higson explained to the Herald that taking the men to court - if they could even be identified - was not an option.

"Police considered the liability of the men involved in the sexual exploitation of the young person during the investigation," he said.

"The offences are 'strict liability' offences under the Prostitution Reform Act 2003 but would still require any charge laid to be proven to gain a conviction."

Kasmeer Lata at sentencing in the High Court at Auckland last week. New Zealand Herald Photograph by Jason Oxenham

Higson said the transactions between the men and Lata - for sex in her Papatoetoe home, motels and other locations - were "almost exclusively made in cash".

That made it "extremely difficult" for police to identify any of the men who paid for the teen's sexual services.

"Throughout the investigation a number of men were interviewed by police, but it was not possible to establish that they offended against the victim in this case," said Higson.

"Ultimately, the only way to prove the identity of the men involved would be for the victim to identify and potentially be called to give evidence against each of them.

"Our focus is on the victim and supporting them throughout the process and this course of action could have caused the victim to be revictimised multiple times and could have caused an extended prosecution phase, which would not have been in [the victim's] best interests."

Higson said the police investigation and prosecution was focused entirely on the primary offenders - Lata and her partner.

"[They] abused their position of trust by exploiting this young person.

"The overriding factor in this case was the views of the victim, who made it clear that she wanted to take proceedings against her mother and partner."

Last week the victim told the Herald she wanted only one thing when she went to police - for her mother to apologise for her wrongdoing.

"I just wanted my mother to acknowledge what she had done. By pleading guilty she showed me that she was sorry - that she knows what she has done is wrong," she said.

"Now it's over - everything is over and I am free to live the life I always wanted to have. I was scared to death, but now I am comfortable."

Justice Matthew Muir said Lata's offending had caused "long-lasting, if not irreparable damage to her daughter" as she "effectively pimped her out".